I don’t think this will impact web apps that much. Even on iOS/iPadOS there are plenty of “apps” that are not native, but mixed web apps instead - take a look at Ionic, PhoneGap or Cordova.

Also progressive web apps are also still gaining in popularity, which are websites that you may install in the Home Screen and allows them to work offline. (Which is not supported on the Mac as far as I know, or just still hidden)

However, what this will do is, further facilitate app development to developers allowing them/us to only maintain one codebase across all Apple platforms.